1. Field of the Invention
The present invention relates to a mobile communication system, and more particularly to a method and apparatus for transmitting a ranging signal, and a method and apparatus for receiving the ranging signal.
2. Discussion of the Related Art
The principal standards established by the Institute of Electrical and Electronics Engineers (IEEE) 802.16 task group are classified into IEEE 802.16-2004 also known as a Fixed WiMAX and an IEEE 802.16e-2005 (hereinafter referred to as ‘16e’) also known as mobile WiMAX. The IEEE Std 802.16e-2005 was finalized by the IEEE on December 2005. Basic standards of a current-version mobile WiMAX technology include IEEE 802.16-2004, IEEE Std 802.16e-2005 (including Corrigenda of IEEE Std 802.16-2004), IEEE Std 802.16-2004/CorI-2005, IEEE Std 802.16f-2005, and IEEE Std 802.16™-2009 (Revision of IEEE Std 802.16-2004, developed by Maintenance Task Group under the draft title “P802.16Rev2”) corrected and integrated on the basis of IEEE Std 802.16g-2007.
Ranging procedure for use in IEEE 802.16e is used for a variety of purposes. In more detail, the ranging procedure is classified into four ranging procedures, i.e., initial ranging, handover ranging, periodic ranging, and bandwidth request ranging. In case of the initial ranging, if a user equipment (UE) attempts to perform initial network entry, the initial ranging is used for acquisition of uplink time synchronization (i.e., time and frequency synchronization). In case of the handover ranging, if connection is changed from a source base station (BS) to a target base station (BS), the handover ranging is used to acquire initial synchronization from the target base station (BS). The periodic ranging enables a user equipment (UE) to periodically update uplink synchronization. The bandwidth request ranging enables a user equipment (UE) to request uplink resources from a base station (BS).
Nowadays, IEEE 802.16m (hereinafter referred to as ‘16m’) standardization for the next-version mobile WiMAX is being intensively conducted in a TGm (802.16 Task Group m) of the IEEE 802.16 task group. The IEEE 802.16m system uses a variety of technologies (e.g., fractional frequency reuse (FFR) and the like) not selected in the previous-version mobile WiMAX. In conclusion, IEEE 802.16m needs to correct the ranging procedure and/or the ranging channel of the IEEE 802.16e according to the aforementioned newly selected technologies.